2,858 research outputs found

    SANTRAUKOS

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    Electronic structure of the Sr0.4Ca13.6Cu24O41Sr_{0.4}Ca_{13.6}Cu_{24}O_{41} incommensurate compound

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    We extracted, from strongly-correlated ab-initio calculations, a complete model for the chain subsystem of the Sr0.4Ca13.6Cu24O41Sr_{0.4}Ca_{13.6}Cu_{24}O_{41} incommensurate compound. A second neighbor tJ+Vt-J+V model has been determined as a function of the fourth crystallographic parameter τ\tau, for both low and room temperature crystallographic structures. The analysis of the obtained model shows the crucial importance of the structural modulations on the electronic structure through the on-site energies and the magnetic interactions. The structural distortions are characterized by their long range effect on the cited parameters that hinder the reliability of analyses such as BVS. One of the most striking results is the existence of antiferromagnetic nearest-neighbor interactions for metal-ligand-metal angles of 9090^\circ. A detailed analysis of the electron localization and spin arrangement is presented as a function of the chain to ladder hole transfer and of the temperature. The obtained spin arrangement is in agreement with antiferromagnetic correlations in the chain direction at low temperature

    Discriminants, symmetrized graph monomials, and sums of squares

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    Motivated by the necessities of the invariant theory of binary forms J. J. Sylvester constructed in 1878 for each graph with possible multiple edges but without loops its symmetrized graph monomial which is a polynomial in the vertex labels of the original graph. In the 20-th century this construction was studied by several authors. We pose the question for which graphs this polynomial is a non-negative resp. a sum of squares. This problem is motivated by a recent conjecture of F. Sottile and E. Mukhin on discriminant of the derivative of a univariate polynomial, and an interesting example of P. and A. Lax of a graph with 4 edges whose symmetrized graph monomial is non-negative but not a sum of squares. We present detailed information about symmetrized graph monomials for graphs with four and six edges, obtained by computer calculations

    Handelshøjskolen i København

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    Agreement with the Creek and Seminole Nations

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    55-2Agreements with the Creeks and Seminoles. [3593] Creek agreement made 27 Sept. 1897; Seminole agreement made 16 Dec. 1897; both provide for allotment of land, for a restructuring of tribal government, etc.; Dawes Commission.1898-2

    Spectrum and decays of kaonic hydrogen

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    By using the non-relativistic effective Lagrangian approach to bound states, a complete expression for the isospin-breaking corrections to the energy levels and the decay widths of kaonic hydrogen is obtained up-to-and-including O(alpha,m_d-m_u) in QCD. It is demonstrated that, although the leading-order corrections at O(alpha^{1/2},(m_d-m_u)^{1/2}) emerging due to the unitarity cusp, are huge, they can be expressed solely in terms of the KN S-wave scattering lengths. Consequently, at leading order, it is possible to derive parameter-free modified Deser-type relations, which can be used to extract the scattering lengths from the hadronic atom data.Comment: 9 pages, 3 postscript figures, epj style. References added, minor revisions in the text, results unchange

    SANTRAUKOS

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    INFORMACIJA AUTORIAMS

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    Letter from the Secretary of the Treasury, transmitting, in answer to Senate resolution of December 16, 1885, statement of certain disallowed accounts, and the reasons for such disallowance.

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    49-1AppropriationsDisallowed Accounts. [2339] Claims, accounts, and vouchers against the U.S. paid by disbursing officers in the Indian service.1886-6
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